Integrated circuit cards are known in which the integrated circuit is mounted in the card by initially making a module having a support film onto which the integrated circuit is fixed via its back face, i.e. via its face opposite from its face in which its connection pads emerge. On a face of the support film opposite from its face on which the integrated circuit is fixed, the support film has contact areas which are generally made prior to the integrated circuit being fixed on the support film. In register with the contact areas, the support film has holes allowing connection wires to pass between the connection areas for the integrated circuit and its connection pads. It will be observed that the integrated circuit has its back towards the contact areas. In order to make the connections between the connection pads of the integrated circuit and the contact areas in a manner that is as simple as possible, chip manufacturers have been requested to arrange connection pads in an order that corresponds to the contact areas so that each link wire can pass directly from a connection pad to a contact area without any need to go round another connection pad or to cross another connection wire.
That type of mount for mounting an integrated circuit in a card is presently the most widespread, but another type of mount has recently appeared in which the integrated circuit is fixed directly in a cavity of the card with the connection pads of the integrated circuit flush with the face of the card that includes the contact areas. An advantageous aspect of that type of mounting is that the contact areas and the linking conductor tracks connecting the contact areas to the connection pads are made by silkscreen printing a conductive polymer after the integrated circuit has been fixed to the card.
It will be observed that in this mounting, the connection pads of the integrated circuit emerge in the face of the card which includes the contact areas, unlike the prior mounting in which the connection pads of the integrated circuit face away from the contact areas. If an integrated circuit designed for mounting in a module is used with the new type of mounting, then the fact of the integrated circuit being turned upside-down inverts the positions of the connection pads relative to the contact areas whose positions are standardized.
Since the contact areas are disposed in two parallel rows, it is naturally possible in the new mounting to choose an orientation for the integrated circuit so that a row of connection pads faces the corresponding row of contact areas. Nevertheless the connection pads of the integrated circuit are still in the opposite order to the contact areas so it is necessary to make linking conductor tracks that go round the contact areas, as shown in FIG. 1, in order to ensure that each integrated circuit connection pad is properly connected to the contact area corresponding thereto. The linking conductor tracks are thus relatively long, and given their small thickness, they present relatively high resistance. In addition, the long length of the linking conductor tracks increases the risk of short circuiting between two linking conductor tracks or the risk of a track being interrupted by lack of conductive material, in particular when the linking conductor tracks are made by silkscreen printing.
As an indication, in the embodiment of FIG. 1, the length of the longest linking conductor track is about 15 mm, and the total length of the linking conductor tracks is about 47 mm. In order to reduce the length of the linking conductor tracks, it would indeed be possible to ask the integrated circuit manufacturer to dispose the connection pads so as to be immediately in register with the corresponding contact areas. Nevertheless, the cost of an integrated circuit depends on the number of circuits of the same kind that are made, and requesting a special integrated circuit for the new mounting would increase the cost of the integrated circuit by an amount that would be unacceptable, given the very fierce competition that exists at present in the field of manufacturing integrated circuit cards.
Also known, from document WO-93/22475, is an integrated circuit having connection pads that emerge in a face of the integrated circuit, where said face is covered in at least a first insulating layer having openings in register with the connection pads, and in which at least one conductor track extends over the first insulating layer and has one end connected to one of the connection pads of the integrated circuit. Nevertheless, that document relates to making solder pads on a face of the integrated circuit and is not concerned in any way with the problem of repositioning integrated circuit pads in a manner that can go as far as fully inverting the initial positioning.